Image recording method and apparatus

ABSTRACT

The present invention is an image recording method and apparatus for recording an image represented by at least two sets of image data separated by colors. Based on the image data, images corresponding to the image data are each recorded on different sections of photosensitive material moving in a sub-scan direction, while the photosensitive materials subjected to main scan by a plurality of light beams. Thereafter, the sections of the photosensitive material are superimposed over one another to produce the final image. Relative positions of the images on each section of photosensitive material are provided to substantially coincide with each other by setting a selected number of blank raster lines in a first main scan for each section of the photosensitive material. As a result, an amount of displacement of each of images on the photosensitive materials is reduced when the sections of photosensitive material are superimposed and aligned with one another to produce the final image. Preferably a blade is used for cutting the photosensitive material into different sections.

This is a divisional of application Ser. No. 09/479,670 filed Jan. 10,2000 now U.S. Pat. No. 6,543,349 issued Apr. 8, 2003; the disclosure ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image recording method and apparatususing a multi-beam, in which an image is recorded by moving a pluralityof light beams relatively to a sub-scan direction of a photosensitivematerial and simultaneously carrying out main scan of a plurality oflight beams, namely, an image recording method and apparatus in which animage is recorded on a photosensitive material by carrying out main scanof a plurality of light beams while the photosensitive material is beingmoved in a sub-scan direction.

2. Description of the Related Art

There has conventionally been known, as a method of recording an imageon a photosensitive planographic printing plate such as a PS plate, amethod in which a photographic film for plate-making (process film) onwhich the image is recorded is superposed on the photosensitiveplanographic printing plate.

The photographic film for plate-making on which the image is recorded isgenerated by image recording processing of an image recording apparatusreferred to as a film setter, and development processing of a developingapparatus.

A magazine in which an elongated photographic film for plate-makingwound in a layered form is accommodated is set in the film setter.

An exposure drum is rotated at a predetermined speed so as to move thephotographic film for plate-making in a sub-scan direction. An imagerecording apparatus is disposed in a radial direction of the peripheralsurface of the exposure drum on which the photographic film forplate-making is closely held.

The image recording apparatus distributes (swings) a plurality of lightbeams emitted from a laser in an axial direction of the exposure drum bya plurality of optical systems (main scan by a multi-beam system). As aresult, main scan is carried out with the plurality of light beams whilethe photographic film for plate-making is being subjected to sub-scan,and the main scan is carried out repeatedly. The light beams aresubjected to on-off control (or duty control) based on imageinformation, and therefore, a predetermined image is recorded on thephotographic film for plate-making.

The photographic film for plate-making on which an image is recorded isguided to an ordinary conveying path and discharged from the filmsetter, and further conveyed to a developing apparatus in a subsequentprocess.

When a print obtained from a photosensitive planographic printing plateis a color image, it is necessary that photosensitive planographicprinting plates be provided respectively for four color components ofcyan (C), magenta (M), yellow (Y), and black (K), that is, four sheetsof photosensitive planographic printing plate, be prepared for eachimage.

Respective relative positions of images recorded on four photosensitiveplanographic printing plates are provided to coincide with one another,and a print of a full-color image can be obtained with four imagesoverlapping with one another.

During recording of images, sub-scan movement of the photographic filmfor plate-making constantly continues, and therefore, recording of animage is started from a starting position of image recording (an initialposition in a region to which light beam is applied in main scan), whichcomes first after a leading end of the photographic film forplate-making, that is, a position of a line at which main scan can bestarted, has been detected by the image recording apparatus. At thistime, there is no correlation between the sub-scan movement of thephotographic film for plate-making and the main scan of light beam.

Accordingly, respective images of the component colors are recorded in astate of being displaced from one another by an amount of about onesub-scan at the maximum. The amount of one sub-scan becomes larger inthe widthwise dimension as a beam number of a multi-beam (the number oflight beams) increases. For example, when exposure is carried out for 96lines/mm using 6 light beams, a beam pitch is about 10 μm, andtherefore, the maximum amount of displacement becomes 60 μm. Anallowable amount of displacement in a print is limited to 100 μm at itsmaximum, and if an amount of displacement at a starting position ofwriting amounts to 60% or more of the allowable amount of displacement,the displacement caused by other factors such as a conveying system, apositioning punch hole, and the like is hardly allowed. As a result,color displacement occurs to thereby deteriorate image quality.

SUMMARY OF THE INVENTION

In view of the above-described circumstances, an object of the presentinvention is to provide an image recording method and apparatus in whichan amount of displacement of relative positions of images on a pluralityof photosensitive materials can be limited to a pitch of one lineirrespective of the beam number of a multi-beam and deterioration ofimage quality caused by color displacement or the like can be prevented.

A first aspect of the present invention is an image recording method,comprising the steps of: (a) providing at least two sets of image dataseparated by color, for an image; (b) recording a separated imagecorresponding to each set of image data on a section of photosensitivematerial moving in a sub-scan direction while the photosensitivematerial is being subjected to main scanning by a plurality of lightbeams; and (c) providing for relative positions of separated images onthe section of photosensitive materials to substantially coincide witheach other by setting a blank raster line in a first main scan for eachsection of the photosensitive material.

A second aspect of the present invention is an image recording methodaccording to the first aspect, wherein in the step of providing forrelative positions of the images, the number of blank raster lines inthe first main scan is set for each section of the photosensitivematerial, based on a distance between a predetermined reference positionon each section of the photosensitive material and a position at whichthe first main scan is started on that section.

A third aspect of the present invention is an image recording methodaccording to the second aspect, wherein as the distance between thepredetermined reference position and the position at which the firstmain scan is started becomes smaller, the number of blank raster linesis set larger.

A fourth aspect of the present invention is an image recording methodaccording to the second aspect, wherein the upper limit of the number ofblank raster lines is equal to the number of light beams in theplurality of light beams, minus one light beam.

A fifth aspect of the present invention is an image recording methodaccording to the first aspect, wherein the blank raster lines are set inorder from a leading end of the sheet of photosensitive material, theblank lines being substantially transverse to a direction in which thesheet of photosensitive material is conveyed.

A sixth aspect of the present invention is an image recording apparatusfor recording an image on photosensitive material, wherein the image isrepresented by at least two sets of image data separated by color, theapparatus comprising:(a) image recording means for recording a separatedimage corresponding to each set of image data on a section ofphotosensitive material, by carrying out main scans of thephotosensitive material with a plurality of light beams; (b)photosensitive material detecting means for detecting that a section ofphotosensitive material has been conveyed to a position at which animage can be recorded thereon; (c) state detecting means for detecting astate in which a main scan by the plurality of light beams can bestarted; (d) controlling means for controlling starting a main scan bythe plurality of light beams, when the controlling means being incommunication with the state detecting means receiving a signaltherefrom that a main scan can be started and the photosensitivematerial detecting means has detected that a section of photosensitivematerial has been conveyed to a position at which an image can berecorded thereon; (e) calculation means for calculating an amount ofdistance by which a section of photosensitive material is conveyed,between a time when the photosensitive material detecting means detectsthat a section of photosensitive material has been conveyed to aposition at which an image can be recorded thereon, and a time when thestate detecting means detects a state in which a main scan by theplurality of light beams can be started; and (f) setting means forsetting a number of blank raster lines in a first scan for each sectionof photosensitive material.

A seventh aspect of the present invention is an image recordingapparatus according to the sixth aspect, wherein the number of blankraster lines in the first main scan is set based on the amount ofdistance by which the section of photosensitive material is conveyed.

An eighth aspect of the present invention is an image recordingapparatus according to the sixth aspect, wherein as the amount ofdistance by which the photosensitive material is conveyed becomessmaller, the number of blank raster lines set by the setting meansincreases.

A ninth aspect of the present invention is an image recording apparatusaccording to the sixth aspect, wherein the upper limit of the number ofblank raster lines is smaller than the number of the plurality of lightbeams by one.

A tenth aspect of the present invention is an image recording apparatusaccording to the sixth aspect, wherein the section of photosensitivematerial includes a leading end and the blank raster lines are set inorder from the leading end of the section of photosensitive material ina direction in which the photosensitive material is conveyed.

An eleventh aspect of the present invention is an image recordingapparatus for recording an image on a photosensitive material, whereinthe image is represented by at least two sets of image data separated bycolor, the apparatus comprising: (a) a conveyor for conveyingphotosensitive material along a conveying path; (b) an image recordingsection having a scanner, in which a plurality of light beams isdirected from the scanner across the conveying path for scanning animage onto photosensitive material being conveyed therealong, the imagerecording section providing a signal indicative of when scanning by theresonant scanner can begin; (c) a sensor which provides a signalindicative of a position of the photosensitive material along theconveying path; and (d) a controller receiving the image data and beingin communication with the image recording section and the sensor, thecontroller receiving the signals from the image recording section andthe sensor, and controlling the image recording section to record animage for each set of image date on different sections of thephotosensitive material, the controller determining an amount a sectionof photosensitive material has been conveyed along the conveying pathbased on when the controller received a signal from the sensor and asignal from the image recording section, wherein the controller controlsthe image scanning section to set a number of blank raster lines in afirst scan of each section of photosensitive material, based on theamount that the respective section of photosensitive material has beenconveyed.

A twelfth aspect of the present invention is an image recordingapparatus according to the eleventh aspect, wherein the scanner is aresonant type scanner.

A thirteenth aspect of the present invention is an image recordingapparatus according to the eleventh aspect, wherein the number of blankraster lines decreases as the amount that the respective section ofphotosensitive material has been conveyed, increases.

A fourteenth aspect of the present invention is an image recordingmethod in which an image is separated into plural image data based onplural colors, and based on the image data, an image is recorded on aphotosensitive material corresponding to each of the image data bycarrying out main scan of a plurality of light beams synchronously withmoving the plurality of light beams relatively to a sub-scan directionof the photosensitive material, the method comprising the steps of:setting, based on a distance from a predetermined reference position oneach photosensitive material to a position at which first main scan isstarted, the number of blank raster lines in the first main scan; andsetting the blank raster lines from a leading end of the photosensitivematerial in a direction in which the photosensitive material isconveyed.

A fifteenth aspect of the present invention is an image recording methodaccording to the fourteenth aspect, wherein the number of blank rasterlines in the first main scan is set for each of the photosensitivematerials so that a position at which main scan is started, whichposition including first image data, with respect to the predeterminedreference position is substantially registered on each of thephotosensitive materials.

A sixteenth aspect of the present invention is an image recording methodusing a multi-beam, in which one image data is separated into at leasttwo colors, and based on the image data separated into at least twocolors, an image is recorded by image recording means carrying out mainscan of a plurality of light beams for an image while moving light beamsrelatively to a sub-scan direction of each of photosensitive materials.In this method, based on an amount of displacement of the photosensitivematerial in the sub-scan direction between a predetermined referenceposition and a position of a line at which main scan is started, blankraster lines of non-image data are set sequentially from the top of theplurality of light beams during the first main scan.

A seventeenth aspect of the present invention is an image recordingmethod using a multi-beam, in which an image is recorded by dividing oneimage data into at least two colors and by carrying out main scan of aplurality of light beams for an image by image recording means whilemoving light beams relatively to a sub-scan direction of each ofphotosensitive materials. This method comprises the steps of: obtainingan amount of displacement in the sub-scan direction of each ofphotosensitive materials corresponding to the same image from apredetermined reference position to a position of a line at which mainscan is started; setting the number of blank raster lines sequentiallyfrom a leading end of the photosensitive material in the sub-scandirection during main scan for other photosensitive materials so thatthe amount of displacement of a photosensitive material located at theposition of a line at which main scan is started, with the amount ofdisplacement being made largest, is limited to a pitch of one line atthe maximum; and setting the top of lines not including the blank rasterlines as an apparent position of a line at which main scan is started.

An eighteenth aspect of the present invention is an image recordingapparatus using a multi-beam, in which based on image data obtained byseparating one image into colors of cyan (C), magenta (M), yellow (Y),and black (BK), an image is recorded by carrying out main scan of N (Nis an integer of 2 or more) light beams by image recording means whilemoving light beams relatively to a sub-scan direction of aphotosensitive material. This apparatus comprises:photosensitive-material detecting means which is provided on a conveyingpath (a conveying path of the photosensitive material or a conveyingpath of light beams) along which light beams are moved relatively to thesub-scan direction of the photosensitive material and which detects arelative position of a line at which main scan is started between thephotosensitive material and the light beams; main-scan-starting-positiondetecting means for detecting a position where recording of an image isstarted in the main scan; start-of-main-scan controlling means whichcontrols the image recording means so as to start main scan after thephotosensitive material and the light beams have reached the relativeposition of a line at which main scan is started by a signal from thephotosensitive-material detecting means and when a signal from themain-scan-starting-position detecting means; calculation means whichcalculates an amount L of relative displacement between thephotosensitive material and the light beams until the main scan isstarted from the relative position of a line at which main scan isstarted between the photosensitive material and the light beams; andblank raster line setting means which sets, based on a ratio R (0≦R<1)of the amount of movement L calculated by the calculation means to apreviously known amount of movement W in one sub-scan, blank rasterlines sequentially from a leading end of the photosensitive material inthe sub-scan direction, which blank raster lines increases as the ratioR becomes smaller with the upper limit of the number of blank rasterlines, N−1, being smaller than the number N of light beams by one in thefirst main scan by the image recording means.

According to the first aspect of the present invention, when one imageis formed by superposing separated images recorded on the respectivephotosensitive materials one another, it is necessary that relativepositions of the separated images on the respective photosensitivematerials be provided to coincide with one another so that the separatedimages can be properly superposed on one another.

When the images are recorded by repeatedly carrying out main scan whilethe photosensitive materials are being subjected to sub-scan, there arecases in which positions at which writing (recording) of the each of theseparated images is started on the respective photosensitive materialsmay be different. Namely, a distance between a predetermined referenceposition on the photosensitive material (for example, a position of theleading end of the photosensitive material) and a position at which thefirst main scan is started varies for each of the photosensitivematerials. Therefore, as the number of light beams (the beam number ofmulti-beam) in one main scan increases, the above-described distance (inthe direction in which the photosensitive material is conveyed) maybecome longer.

For this reason in the first main scan, blank raster lines of non-imagedata are set. Namely, by setting a non-recording region (line) on thephotosensitive material, an actual position at which recording of animage is started can be displaced backward in the direction in which thephotosensitive material is conveyed, and the positions at whichrecording of the images are started on the photosensitive materials canbe made coincident with one another.

An optical system used for the main scan, for example, a polygon mirroror a resonant mirror, is provided to mechanically swing (rotate) asurface by which a light beam is reflected so as to distribute the lightbeam on the photosensitive material in a main scan direction. For thisreason, when the photosensitive material is conveyed to a position inwhich recording of an image can be started immediately after the opticalsystem is brought into an initial state (that is, a state in which mainscan for the photosensitive material can be started), recording of theimage is cannot be carried out until the optical system is brought intothe initial state again. On the other hand, when the optical system isbrought into the initial state synchronously with (or immediately after)the photosensitive material having been conveyed to the position atwhich recording of an image can be started, recording of the image canbe started immediately.

As described above, when the time at which the main scan is startedvaries greatly, the relative positions of the separated images on therespective photosensitive materials do not coincide with one another dueto sub-scan for the photosensitive material is being continuouslycarried out.

Accordingly, as described in the second and fifth aspects of the presentinvention, the number of blank raster lines in the first main scan isset for each section of the photosensitive material, based on a distancebetween a predetermined reference position on each section of thephotosensitive material and a position at which the first main scan isstarted on that section, also, the blank raster lines are set in orderfrom a leading end of the sheet of photosensitive material, the blanklines being substantially transverse to a direction in which the sheetof photosensitive material is conveyed.

For this reason, based on the distance in the direction in which thephotosensitive material is conveyed, in the first main scan, blankraster lines of non-image data are set sequentially from the leading endof the photosensitive material in the direction in which thephotosensitive material is conveyed. Namely, by setting a non-recordingregion (line) on the photosensitive material, an actual position atwhich recording of an image is started can be displaced, based on thedistance in the conveying direction, backward in the direction in whichthe photosensitive material is conveyed, and the positions at whichrecording of the images are started on the photosensitive materials canbe made coincident with one another.

As a result, the relative positions of the separated images on therespective photosensitive materials can be made coincident with oneanother.

A sixth aspect of the present invention is an image recording apparatusin which an image is recorded by applying a plurality of light beams(for example, N light beams) on photosensitive materials for each of thecolors C, M, Y, and K which are required for forming a so-calledfull-color image or the like. According to the sixth aspect of thepresent invention, the state in which the photosensitive material isconveyed to the position at which recording of an image can be startedis detected by the photosensitive-material detecting means (sensor), andsubsequently, the state in which main scan by the plurality of lightbeams can be started is detected by a means (sensor) for detecting thestate in which a main scan can be started.

When the state in which main scan by the plurality of light beams can bestarted is detected by the sensor for detecting the state in which amain scan can be started after the state in which the photosensitivematerial is conveyed to the position at which an image can be recordedis detected by the photosensitive-material detecting sensor, namely,after a predetermined signal is outputted from thephotosensitive-material detecting sensor and when a predetermined signalis outputted from the sensor for detecting the state in which a mainscan can be started, the sensor for controlling start of main scan whichis provided to control the image recording means (section) starts mainscan. At this time, the position at which recording of an image isstarted on each photosensitive material may be displaced in the sub-scandirection by an amount W of movement for one sub-scan at the maximum.The amount W of movement for one sub-scan corresponds to an amount bywhich the photosensitive material is conveyed in one main scan, and asthe number of light beams increases, the amount W of movement becomeslarger.

A calculation means (data processor) calculates an amount L by which thephotosensitive material is conveyed during a time between a time atwhich the state in which the photosensitive material is conveyed to theposition in which an image can be recorded is detected by thephotosensitive-material detecting sensor, and a time at which the statein which main scan by the plurality of light beams can be started isdetected by the sensor for detecting the state in which main scan can bestarted. The ratio R (0<R≦1) of the amount L by which the photosensitivematerial is conveyed with respect to the amount W of movement for onesub-scan is obtained.

In the first main scan as in the seventh to tenth aspects of the presentinvention, blank raster lines whose number increases as the ratio Rbecomes smaller are set, based on the above-described ratio R,sequentially from the leading end of the photosensitive material in thedirection in which the photosensitive material is conveyed. The upperlimit of the number of blank raster lines is smaller than the number Nof light beams by one.

Accordingly, in the case of “the most suitable timing”, the first mainscan lines, N−1, are blank raster lines, and the position at whichrecording of an image is started in the case of “the most unsuitabletiming” is displaced only by a pitch of one line at the maximum. As aresult, an image of high quality in which no color displacement occurscan be obtained.

According to the sixteenth aspect of the present invention, when oneimage is formed by superposing images recorded on the photosensitivematerials one another, it is important that these images be registered.Further, it is necessary that relative positions of images andphotosensitive materials be provided to coincide with one another.

When an image is recorded by carrying out main scan repeatedly whilemoving the light beams relative to the sub-scan direction of thephotosensitive material, a position at which writing is started may varybetween photosensitive materials. Namely, the time that the relativeposition between the photosensitive material and the light beams reachesfrom a predetermined reference position on the photosensitive material(for example, a leading end of the photosensitive material) to theposition of a line at which main scan is started has no correlation withone another, and therefore, as the number of multi-beams increases, anamount of displacement in the sub-scan direction becomes larger.

For this reason, based on the amount of displacement of thephotosensitive material in the sub-scan direction, blank raster lines ofnon-image data are set sequentially from the top of the plurality oflight beams during the first main scan. Namely, by providing linesapparently having nothing recorded therein, a leading end of an image isdisplaced backward in the sub-scan direction of the photosensitivematerial by a region of the blank raster lines so as to correspond to aphotosensitive material displaced by the largest amount.

According to the seventeenth aspect of the present invention, an amountof displacement of the photosensitive material in the sub-scan directionfrom a predetermined reference position (for example, the leading end ofthe photosensitive material) to the position of a line at which mainscan is started is obtained.

An optical system used for the main scan, for example, a polygon mirroror a resonant mirror, is provided to mechanically swing (rotate) asurface by which a light beam is reflected so as to distribute the lightbeam on the photosensitive material in a main scan direction. For thisreason, when the photosensitive material and the light beam reach therelative position of a line at which main scan is started immediatelyafter the optical system passes an initial position, recording of theimage cannot be carried out until the optical system is brought into theinitial state again. On the other hand, when the optical system isbrought into the initial state immediately after the photosensitivematerial and the light beam has reached the relative position of a lineat which main scan is started, recording of the image can be startedimmediately.

As described above, when the time at which the main scan is startedvaries greatly, the relative positions of images on the photosensitivematerials do not coincide with one another due to sub-scan for thephotosensitive material being continuously carried out.

The number of blank raster lines are set sequentially from a leading endin the sub-scan direction of a photosensitive material at a position ofa line at which main scan is started, which the position is displaced bythe largest amount, in the main scan for other photosensitive materials,and the top of lines not including the blank raster lines is set as anapparent line at which recording of an image is started. As a result,the photosensitive material displaced by the largest amount is limitedto an amount of displacement of pitch of one line at the maximum, andtherefore, the amount of displacement can be regarded as that in anallowable range.

The eighteenth aspect of the present invention is an apparatus forrecording an image by applying a multi-beam (N light beams) to foursheets of photosensitive material for colors of C, M, Y, and BK whichare required for forming a so-called full-color image. According to thisaspect, the position of a line at which main scan is started is detectedby the photosensitive-material detecting means, and subsequently, theposition at which recording of an image is started is detected by thestart-of-main-scan detecting means.

The calculation means calculates the amount of relative movement Lbetween the photosensitive material and the light beam until the mainscan is started from the relative position of a line at which main scanis started between the photosensitive material and the light beam, andthe ratio R (0≦R<1) of the amount of movement L to the amount ofmovement W in one sub-scan is obtained.

Blank raster lines whose number increases as the ratio R becomes smallerare set, based on the above-described ratio R, sequentially from theleading end of the photosensitive material in the direction in which thephotosensitive material is conveyed (blank raster line setting means).The upper limit of the number of blank raster lines is smaller than thenumber N of light beams by one.

Accordingly, in the case of “the most suitable timing”, the first mainscan lines, N−1, are blank raster lines, and the position at whichrecording of an image is started in the case of “the most unsuitabletiming” is displaced only by a pitch of one line at the maximum. As aresult, an image of high quality in which no color displacement occurscan be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a film setter according toan embodiment of the present invention.

FIG. 2 is a perspective view of an image exposure section.

FIG. 3A is a schematic diagram of a movable guide portion applied to theembodiment of the present invention; and FIG. 3B is a schematic diagramof a movable guide portion according to a modified example.

FIG. 4A and FIG. 4B are photographic film for plate-making feed controlroutine.

FIG. 5 is a control routine of image recording for a photographic filmfor plate-making.

FIG. 6 is a sub-routine showing details of image recording processing.

FIG. 7 is a diagram comprised of a plurality of patterns for determininga number S of blank raster lines at an initial stage of main scan.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a schematic structural diagram of a film setter 100 whichserves as an image processing apparatus for a photographic film forplate-making according to the present invention.

A photographic film for plate-making 102 is wound into a reel 104 in anelongated state and is accommodated in a magazine 106. The magazine 106can be loaded at a predetermined position in an apparatus main body 108.

The photographic film for plate-making 102 pulled out from the magazine106 is nipped by a pair of conveying rollers 110A and 110B formed as afeed roller 110.

One conveying roller 110A (or 110B) of the feed roller 110 receivesdriving force from a motor 112 via speed changing means (not shown). Thephotographic film for plate-making 102 is pulled out from the magazine106 by being nipped by the conveying rollers 110A and 110B and isconveyed to an exposure drum 114.

The exposure drum 114 receives driving force of the motor 116 via speedchanging means (not shown) and is driven to rotate at the same linearvelocity as that at which the photographic film for plate-making 102 isconveyed by the feed roller 110 (that is, the speed at which thephotographic film for plate-making 102 is conveyed by the feed roller110 is equal to that at which the photographic film for plate-making 102is conveyed by the exposure drum 114).

Nip rollers 118 and 120 are disposed at two different positions on aperipheral surface of the exposure drum 114.

The surface of the nip roller 118 is made of metal. The photographicfilm for plate-making 102 sent out from the feed roller 110 is insertedand nipped between the nip roller 118 and the exposure drum 114. Thephotographic film for plate-making 102 thus nipped is wound onto theperipheral surface of the exposure drum 114. The state in which the film102 is wound onto the exposure drum 114 is continuously maintained to aposition where the film 102 is subsequently nipped by another nip roller120 and the exposure drum 114.

The surface of the nip roller 120 is made of rubber. The photographicfilm for plate-making 102 is separated from the exposure drum 114 at theposition between the nip roller 120 and the exposure drum 114 and isconveyed to an ordinary conveying path NR formed by arrangement of aplurality of conveying roller pairs 122.

The motors 112 and 116 drive to allow normal rotation and reverserotation of the feed roller 110 and the exposure drum 114 based on acontrol signal from a controller 124. Namely, during ordinary normalrotation of the exposure drum 114, the exposure drum 114 receives thephotographic film for plate-making 102 from the feed roller 110 andconveys the same to the ordinary conveying path NR, but during reverserotation of the exposure drum 114, the exposure drum 114 can also conveythe photographic film for plate-making 102 back to the feed roller 110.

The controller 124 adjusts driving torque of the exposure drum 114 bythe motor 116 for rotating the exposure drum 114. Namely, the exposuredrum 114 is controlled so as to rotate at a relatively high torqueduring the normal rotation and rotate at a relatively low torque duringthe reverse rotation.

The low torque is set such that when the photographic film forplate-making 102 is nipped and conveyed (backward) by the nip rollers118, 120, and the exposure drum 114, the photographic film forplate-making 102 is strained at a predetermined tension without beingbroken.

Above a region in which the photographic film for plate-making 102 iswound onto the exposure drum 114, an image recording section 126 isdisposed.

As shown in FIG. 2, the image recording section 126 includes ahelium-neon laser 128 (hereinafter referred to simply as a laser 128).

The controller 124 stores therein image information, and based on thestored image information, the controller 124 controls an acoustoopticelement (AOM) 132 so that output of a plurality of light beams (anon-off action of light beams) is controlled.

A light beam outputted from the laser 128 is inputted to the AOM 132 viaa reflecting mirror 130 and divided into a plurality of light beams (inthe present embodiment, six light beams) and further inputted to aresonant scanner 134 via a reflecting mirror 133. The resonant scanner134 has a function of distributing six light beams so that the six lightbeams are scanned along a main scan direction of the photographic filmfor plate-making 102. The light beams distributed in the resonantscanner 134 are scanned on the exposure drum 114 via a scanning lens 136and two reflecting mirrors 137 and 139. The six light beams are arrangedin a sub-scan direction on the photographic film for plate-making 102and an image corresponding to six main scan lines is recorded on thephotographic film for plate-making in one main scan.

At this time, the exposure drum 114 rotates at a constant speed tothereby allow the photographic film for plate-making 102 to move in thesub-scan direction. For this reason, the photographic film forplate-making 102 is subjected to sub-scan while six main scan lines arebeing recorded thereon, and by repeatedly carrying out theabove-described processing, an image based on the image information canbe recorded on the photographic film for plate-making 102.

A leading-end detecting sensor 115 for detecting a leading end of thephotographic film for plate-making 102 in a direction in which the filmis conveyed is disposed in the vicinity of the exposure drum 114 and adetermination is made by the sensor 115 as to whether the photographicfilm for plate-making 102 reaches a position where an image can berecorded thereon.

Accordingly, after the leading end of the photographic film forplate-making 102 has been detected by the leading-end detecting sensor115, recording of an image is started from the time at which theresonant scanner 134 is brought into an initial state which will bedescribed later.

A cutter portion 138 is disposed along the ordinary conveying path NR soas to allow the photographic film for plate-making 102 having an imagerecorded on the exposure drum 114 to be cut to a predetermined length.The photographic film for plate-making 102 as cut into a sheet isdischarged from the film setter 100 and conveyed to a developingapparatus (not shown) in a subsequent process.

The film setter 100 of the present embodiment is equipped with a punchunit 140 by which a positioning punch hole is formed in the photographicfilm for plate-making 102.

The punch unit 140 is provided at the end of a branch path DR branchedout from the ordinary conveying path NR at a downstream side of theexposure drum 114.

The branch path DR starts from a point at which the photographic filmfor plate-making 102 is nipped by the nip roller 120 and the exposuredrum 114, and is formed so as to extend from the starting point thereofdownward a little more than the ordinary conveying path NR (in a lowerleft direction on the paper of FIG. 1 at an angle of about 45 degrees tothe direction of the ordinary conveying path NR).

A determination as to whether the photographic film for plate-making 102is guided to the ordinary conveying path NR or guided to the branch pathDR is made by the necessity for formation of a punch hole, or not. Basedon this determination, a movable guide portion 142 guides thephotographic film for plate-making 102 in a desired direction.

As shown in FIG. 3A, the movable guide portion 142 includes, at a branchpoint of the ordinary conveying path NR and the branch path DR, a point150 whose one end is supported in a swingable manner, and by swingingthe point 150, any one conveying path can be selected.

As another structure of the movable guide portion 142, as shown in FIG.3B, three rollers 144, 146, and 148 may be used to form the same. Thethree rollers 144, 146, and 148 are arranged in a vertical directioninto contact with one another. The central roller 146 is a drivingroller which rotates in normal and reverse directions.

When the photographic film for plate-making 102 is guided to theordinary conveying path NR, the central roller 146 is rotated in acounterclockwise direction. As a result, the photographic film forplate-making 102 is nipped by the upper roller 144 and the centralroller 146 and is guided and conveyed to the conveying path NR. When theleading end of the photographic film for plate-making 102 is conveyed toa lower side of the central roller 146, the leading end of thephotographic film for plate-making 102 is pushed up toward the centralroller 146 by the rotation of the lower roller 148.

On the other hand, when the photographic film for plate-making 102 isguided to the branch path DR, the central roller 146 is rotated in aclockwise direction. As a result, the photographic film for plate-making102 is nipped by the lower roller 148 and the central roller 146 and isguided and conveyed to the branch path DR. When the leading end of thephotographic film for plate-making 102 is conveyed to an upper side ofthe central roller 146, the leading end of the photographic film forplate-making 102 is pushed down toward the central roller 146 by therotation of the upper roller 144.

The conveying path may be changed in a point-switching manner byproviding a conveying guide plate for changing the conveying pathwithout using the three rollers 144, 146, and 148.

A guide plate 152 is disposed on the branch path DR between the exposuredrum 114 and the punch unit 140 so that the photographic film forplate-making 102 can reliably be conveyed to the punch unit 140.

The punch unit 140 is connected to the controller 124 via a driver 154.The punch unit 140 is equipped with a male cutting part and a femalecutting part. The male cutting part is moved by driving force of thedriver 154 in a state in which the photographic film for plate-making102 is interposed between the male and female cutting parts, and isfurther engaged with the female cutting part. As a result, a punch holeof a predetermined shape (for example, a circular hole) is formed in thephotographic film for plate-making 102.

Further, a leading-end detecting sensor 156 is provided in the punchunit 140 and controls so that the male cutting part is engaged with thefemale cutting part at the point in time of detecting the leading end ofthe photographic film for plate-making 102.

The state in which the male cutting part is engaged with the femalecutting part is maintained for a predetermined time, and thereafter,this state is cancelled. During the above-described state, thephotographic film for plate-making 102 is conveyed backward by thereverse rotation of the exposure drum 114 and a slack of thephotographic film for plate-making 102 formed between the exposure drum114 and a position at which the male and female cutting parts areengaged is eliminated. The photographic film for plate-making 102 isthereby brought into a state of strain or tension. In this case, theexposure drum 114 rotates in reverse at a low torque as described above,and therefore, there is minimal risk of the photographic film forplate-making 102 being broken.

A rotary encoder 158 is mounted to the exposure drum 114 and an outputsignal of the rotary encoder 158 is supplied to the controller 124. Thecontroller 124 resets the output signal from the rotary encoder 158 apredetermined time after the reverse rotation of the exposure drum 114is started, and counts the output signals until the leading end of thephotographic film for plate-making 102 reaches an exposure startingposition in the image recording section 126.

In FIG. 4A and FIG. 4B, in step 200, an image recording mode is inputtedand set by an operation panel (not shown). This recording mode isprovided to make a determination as to whether an image to be recordedis a monochrome (black-and-white) image or a color image. In a case of amonochrome image, one photographic film for plate-making 102 isprepared. In a case of a color image, four photographic films forplate-making 102 for colors of C, M, Y, and K are prepared.

In step 202, the photographic film for plate-making 102 is pulled outfrom the magazine 106. In the subsequent steps 204 and 206, the feedroller 110 is driven to rotate in a normal direction and the exposuredrum 114 is also driven to rotate in a normal direction.

In step 208, it is determined whether formation of a punch hole isrequired. Namely, a determination is made as to whether formation of apunch hole for positioning the four photographic films for plate-making102 which are required for a color image is necessary. Thisdetermination depends on the recording mode set in step 200.

When it is determined that formation of a punch hole is necessary instep 208, that is, when an image to be recorded is a color image, theprocess proceeds to step 210, in which the movable guide portion 142 isset in a state of guiding a film to the branch path DR.

As a result, the photographic film for plate-making 102 nipped andconveyed by the feed roller 110 and wound onto a portion of theperipheral surface of the exposure drum 114 by the nip rollers 118 and120 is conveyed to the end of the branch path DR at which the punch unit140 is disposed.

In step 212, it is determined whether the leading end of thephotographic film for plate-making 102 is detected in the leading-enddetecting sensor 156 provided in the punch unit 140. When the decisionof step 212 is made affirmative, the process proceeds to step 214, inwhich driving of the feed roller 110 and the exposure drum 114 isstopped.

In the subsequent step 216, the male cutting part is engaged with thefemale cutting part so as to allow formation of a punch hole.

In step 218, the exposure drum 114 is driven to rotate in a reversedirection. At this time, in the present embodiment, the male cuttingpart is in an insertion state in the punch hole, that is, engaged withthe female cutting part. For this reason, if there was slack in thephotographic film for plate-making 102, the slack is eliminated and thephotographic film for plate-making 102 is strained or tensioned.

In the present embodiment, the exposure drum 114 is rotated in thereverse direction at a low driving torque. Accordingly, the photographicfilm for plate-making 102 is maintained at a predetermined amount oftension, when the photographic film for plate-making 102 is in the stateof being tensioned or strained, so that there little possibility that aregion of the photographic film for plate-making 102 in the vicinity ofthe punch hole will be broken or ripped by the male cutting part.

When it is determined that a predetermined time has elapsed in step 220,in step 224, a count value in the rotary encoder 158 is reset. Namely,the count value is reset when the photographic film for plate-making 102is at a predetermined amount of tension or strain between the exposuredrum 114 and the punch unit 140, and therefore, the count value can bereset under the same conditions each time (and at the same position).

In step 226, driving of the exposure drum 114 is stopped so that themale cutting part held in a state of being engaged with the punch hole,is disengaged from the female cutting part (the punching operation isterminated). In step 228, the exposure drum 114 and the feed roller 110are driven to rotate in the reverse direction.

When the photographic film for plate-making 102 is conveyed backwardafter the punching operation has been terminated, the count value ofrotary encoder 158 mounted to the exposure drum 114 is counted from areset state. The photographic film for plate-making 102 is conveyedbackward until the count value reaches a predetermined value.

When in step 230 it is determined that the count value of the rotaryencoder 158 reaches the predetermined value, the process proceeds tostep 232, in which the reverse rotation of the feed roller 110 and theexposure drum 114 is stopped, and thereafter, the process furtherproceeds to step 234.

When in step 208 it is determined that the formation of the punch holeis not necessary, that is, when an image to be recorded is a monochromeimage, the process proceeds from step 208 to step 234. In step 234, themovable guide portion is set in a state of guiding the film to theordinary conveying path NR and the process proceeds to an imagerecording control routine shown in FIG. 5.

As shown in FIG. 5, in step 250, the feed roller 110 and the exposuredrum 114 are driven to rotate in a normal direction, and in thesubsequent step 252, it is determined whether the leading end of thephotographic film for plate-making 102 is detected by the leading-enddetecting sensor 115 in the vicinity of the exposure drum 114.

When the decision of step 252 is made affirmative, it is determined thatthe leading end of the photographic film for plate-making 102 hasreached a predetermined position, and in step 254, image recordingprocessing is performed. In the image recording processing, main scan ofa multi-beam (six light beams) is started, synchronously with a signalindicating that the resonant scanner 134 in a state in which main scanof the photographic film for plate-making 102 can start (that is, aninitial state). Sub-scanning is continuously carried out due to rotationof the exposure drum 114. Therefore, recording for an amount of oneimage ends after repeated main scans as above-described. The imagerecording processing will be described later with reference to the flowcharts shown in FIGS. 6 and 7.

When the sub-scan is carried out for a predetermined region of the filmafter completion of the image recording (step 256). Namely, when thephotographic film for plate-making 102 is conveyed a predeterminedamount, driving of the feed roller 110 and the exposure drum 114 isstopped (step 258). In step 260, the cutter portion 138 is operated tocut the photographic film for plate-making 102 into a plurality ofsheets every one image. The photographic films for plate-making 102,after they have been cut into sheets, are nipped and conveyed by theconveying roller pairs 122 and discharged from the film setter 100.

In step 262, the remaining photographic film for plate-making 102 (in anelongated or un-cut state) is conveyed backward by rotating the feedroller 110 and the exposure drum 114 in reverse.

In step 264, it is determined whether the count value of the rotaryencode 158 has reached a predetermined value during the backwardconveying of the film. When the decision of step 264 is affirmative, itis determined that the count value has reached the same value as in step230 in FIG. 4. Thus in step 266, the reverse rotation of the feed roller110 and the exposure drum 114 is stopped.

In step 268, it is determined whether the processing must continue. Ifprocessing must continue, the process returns to step 200 in FIG. 4.Otherwise, the process ends.

FIG. 6 shows a sub-routine of the image recording processing.

In step 270, the feed roller 110 and the exposure drum 114 are driven torotate in the normal direction. In the subsequent step 272, it isdetermined whether the film has reached the position of a line at whichmain scan is started.

When the decision of step 272 is affirmative, a signal indicatingstarting of image recording is output (step 274).

In step 276, a ratio R of an amount L by which the photographic film forplate-making 102 moves in the sub-scan direction, which amountcorresponds to a time difference between a time at which the signalwhich indicates starting of image recording is outputted, and a time atwhich a signal indicating that the resonant scanner is brought into theabove-described initial state is outputted, and one sub-scan width W (anamount by which the photographic film for plate-making 102 moves in thesub-scan direction during one main scan), that is, L/W=R, is calculated.Subsequently, in step 278, based on the calculated ratio R, the number Sof blank raster lines in a region (initial region) of the photographicfilm for plate-making 102 on which six lines (image) are to be recordedin the first main scan after outputting of the signal which indicatesstarting of image recording is set.

In the description given below, the amount L by which the film moves,and the sub-scan width W are each would be represented by the number oflines recorded on the photographic film for plate-making 102 by the mainscan of light beams.

In step 280, image data is read based on the set number S of blankraster lines.

The position at which recording (writing) on the photographic film forplate-making 102 is started greatly varies between “the most suitabletiming” (when the time difference between the time at which the signalwhich indicates starting recording of an image is outputted, and thetime at which the signal which indicates that the resonant scanner isbrought into the above-described initial state is outputted is theshortest) and “the most unsuitable timing” (when the time differencebetween the time at which the signal which indicates starting recordingof an image is outputted, and the time at which the signal whichindicates that the resonant scanner is brought into the above-describedinitial state is outputted is the longest). Namely, the position atwhich recording on the photographic film for plate-making 102 is startedat “the most unsuitable timing” is displaced from that at “the mostsuitable timing” by an amount by which the photographic film forplate-making 102 moves in the sub-scan direction during one main scan.In the present embodiment, the number N of multi-beam is 6, andtherefore, respective recording start positions at “the most unsuitabletiming” and “the most suitable timing” are displaced from each other byan amount of 6 lines.

The main scan line width is about 10 μm and an allowable range of colordisplacement in a print is 100 μm at its maximum. When an amount ofdisplacement of the recording start position is that of 6 lines, thatis, 60 μm, it amounts to a larger part of the allowable range. In thiscase, when displacement caused by other factors (for example,positioning of four sheets of photographic film for plate-making 102)occur, a total amount of displacement immediately exceeds the allowablerange, thereby resulting in deterioration of the quality of a finishedimage.

Accordingly, in the present embodiment, based on the above-describedratio R (=L/W), in the first main scan, only one line is recorded at thelowest end (a position at which a sixth line is to be recorded) in aregion of the photographic film for plate-making 102 on which 6 linesare to be recorded, that is, an initial region. Blank raster lines are“recorded” in a remaining region of the initial region (in which thefirst to fifth lines are to be recorded). Namely, nothing is recorded inthe region in which the first to fifth lines are recorded in the firstmain scan. As a result, in a conventional system, the recording startposition on the photographic film for plate-making 102 at “the mostunsuitable timing” and the recording start position on the photographicfilm for plate-making 102 in cases other than “the most unsuitabletiming” are displaced from each other by the amount of 6 lines at themaximum. However, in the present embodiment, the amount of displacementbetween the respective recording start positions is limited to one lineat the maximum.

As shown in FIG. 7, a pattern A indicates a case in which the resonantscanner 134 is brought into the above-described initial stateimmediately after the photographic film for plate-making 102 has reachedthe position of a line at which main scan is started, and is an exampleof “the most suitable timing”. For this reason, 6 light beams can all bewritten in the above-described initial region. However, in the presentembodiment, even in this case, five light beams are used as blank rasterlines, and only one line is recorded at the lowest end of the initialregion with no line being recorded in the region in which the first tofifth lines are to be recorded.

Patterns B to F each indicate an example in which the resonant scanner134 is brought into the above-described initial state after thephotographic film for plate-making 102 has reached the position of aline at which main scan is started. The number S of blank raster linesis determined in each of the examples. Namely, as the time differencebetween the time at which the signal which indicates starting of imagerecording is outputted and the time at which the signal which indicatesthat the resonant scanner is brought into the above-described initialstate is outputted becomes short, the number S of blank raster linesincreases. Further, as the time difference between the time at which thesignal which indicates starting of image recording is outputted and thetime at which the signal which indicates that the resonant scanner isbrought into the above-described initial state is outputted becomeslonger, the number S of blank raster lines decreases.

The pattern F indicates an example in which the resonant scanner 134 isbrought into the initial state immediately before the photographic filmfor plate-making 102 reaches the position of a line at which main scanis started, and is an example of “the most unsuitable timing”. In thiscase, the photographic film for plate-making 102 is conveyed in thesub-scan direction for the longest time until the first main scanstarts.

The above-described pattern A is set as the maximum value, N−1, of thenumber S of blank raster lines, and subsequently, by setting respectiveregions of the patterns B to F and decreasing the number S of blankraster lines one by one, only remaining lines which are other than theblank raster lines at the first scan are recorded based on image data.As a result, even in a case of image recording based on any pattern, theamount of displacement can be limited to one line at the maximum.

In step 282 shown in FIG. 6, main scan is started. The first main scanfor the photographic film for plate-making 102 is carried out based onthe number S of blank raster lines, which is determined in accordancewith any one of the above-described patterns A to F. The amount ofdisplacement between the four sheets of photographic film forplate-making 102 in the case of a color image is a width of one line atthe maximum and no more displacement is caused. As a result,deterioration of image quality, such as color displacement can bereduced. Further, the amount of displacement is thus reduced, andtherefore, displacement caused by other factors (for example,positioning of a punch hole) is allowable to a certain extent, and anallowable amount of displacement of 100 μm can be effectively utilized.

An image is recorded as raster lines whose number is the same as thenumber of a plurality of light beams for each main scan, and recordingof the image is completed at the point in time that all raster lines ofone image plane have been recorded. At this time, at final main scan,the plurality of light beams (in this embodiment, six light beams) arenot necessarily used to form image data. In the final main scan, on-offcontrol only for the required number of light beams is made based onimage data, and remaining light beams are set as blank raster lines ofnon-image data. In step 284, it is determined whether the sub-scan for aregion of one image is completed. When the decision of step 284 isaffirmative, this routine ends.

The image processing apparatus for a photographic film for plate-makingshown in FIG. 1 is an example of a system in which light beams are movedrelatively to the sub-scan direction of the photosensitive materialwhile conveying the photographic film for plate-making by feed rollers,nip rollers and exposure drum.

On the other hand, the present invention can also be applied to a systemin which one image plane is recorded by moving light beams both in themain scan direction and in the sub-scan direction with a photosensitivematerial being fixed to an inner surface of an exposure drum (i.e., aninner drum system) or to a system in which one image plane is recordedwhile moving light beams in the sub-scan direction by rotating anexposure drum together with the photosensitive material at a high speed(main scan) with a photosensitive material being wound onto an outerperiphery of an exposure drum (i.e., an outer drum system).

What is claimed is:
 1. An image recording apparatus for recording animage on photosensitive material, wherein the image is represented by atleast two sets of image data separated by color, the apparatuscomprising: an image recording section for recording a separated imagecorresponding to each set of the image data on a section of thephotosensitive material, by carrying out main scanning of thephotosensitive material with a plurality of light beams; aphotosensitive material detecting section for detecting that the sectionof photosensitive material has been conveyed to a position at which theseparated image can be recorded thereon; a state detecting section fordetecting a state in which the main scanning by the plurality of lightbeams can be started; a controlling section for controlling starting themain scanning by the plurality of light beams when the state detectingsection detects the state in which the main scanning by the plurality oflight beams can be started after the photosensitive material detectingsection detects that the section of photosensitive material has beenconveyed to the position at which the separated image can be recordedthereon; a calculation section for calculating an amount of distance bywhich the section of photosensitive material is conveyed, between a timewhen the photosensitive material detecting section detects that thesection of photosensitive material has been conveyed to the position atwhich the separated image can be recorded thereon, and a time when thestate detecting section detects the state in which the main scanning bythe plurality of light beams can be started; and a setting section forsetting a number of blank raster lines in a first main scan of the mainscanning for each section of photosensitive material on the basis of thecalculated amount of distance by the calculation section.
 2. An imagerecording apparatus according to claim 1, wherein as the amount ofdistance by which the photosensitive material is conveyed becomessmaller, the number of blank raster lines set by the setting sectionincreases.
 3. An image recording apparatus according to claim 1, whereinthe upper limit of the number of blank raster lines is smaller than thenumber of the plurality of light beams by one.
 4. An image recordingapparatus according to claim 1, wherein the section of photosensitivematerial includes a leading end and the blank raster lines are set inorder from the leading end of the section of photosensitive material ina direction in which the photosensitive material is conveyed.
 5. Animage recording apparatus according to claim 1, wherein the imagerecording section has a scanner, from which the plurality of light beamsare directed across a conveying path of the photosensitive material forscanning the separated image onto the photosensitive material beingconveyed therealong, the state detecting section provides a signalindicative of the state in which the main scanning by the plurality oflight beams can be started, the photosensitive material detectingsection provides a signal indicative of that the section ofphotosensitive material has been conveyed to the position at which theseparated image can be recorded thereon, the calculation sectioncalculates the amount of distance on the basis of the signals, therebythe separated image for each set of image date is recorded on differentsections of the photosensitive material.
 6. An image recording apparatusaccording to claim 5, wherein the scanner is a resonant type scanner. 7.An image recording apparatus according to claim 5, wherein the number ofblank raster lines decreases as the amount that the respective sectionof photosensitive material has been conveyed, increases.
 8. An imagerecording apparatus according to claim 5, wherein the setting sectionsets the number of blank raster lines based on the amount of distancethat the respective section of photosensitive material has beenconveyed.
 9. An image recording apparatus according to claim 5, whereinthe setting section is in communication with the photosensitive materialdetecting section and the state detecting section.
 10. An imagerecording apparatus according to claim 5, further comprising a blademounted along a cutting path, which cuts the photosensitive materialinto different sections.